1. Field of the Invention
The present invention relates generally to an oil pump arrangement for a marine drive, and more particularly to an improved seal arrangement for an oil pump that is driven by a rotating shaft.
2. Description of the Related Art
An outboard motor typically comprises a power head and a housing unit that depends from the power head. The power head includes an internal combustion engine generally configured to drive a vertically-extending crankshaft that is coupled with a driveshaft. The driveshaft depends into the housing unit and drives a propulsion device of the outboard motor.
A lubrication system distributes lubricant to various engine components. The lubrication system can include an oil pump that circumferentially surrounds and is driven by the crankshaft and/or driveshaft. A seal arrangement can be provided in order to minimize oil leakage from the oil pump. Such a seal arrangement can include a seal member disposed below the oil pump chamber and configured to engage the surface of the crankshaft so that oil from the pump will not leak downwardly past the seal member. Such oil leakage is wasteful and can cause damage to other outboard motor components.
A cooling system of the outboard motor can direct a flow of water through a driveshaft housing in order to cool some components and systems such as, for example, and exhaust system. During operation of the outboard motor, at least some of the water in the housing can often splash onto the oil pump. The seal member is configured to stop oil from the oil pump from leaking downwardly past the seal, and is not as effective at inhibiting splashed water from invading upwardly past the seal member and into the oil pump. Such invading water mixes with oil in the oil pump and causes an emulsion effect, which quickens deterioration of the oil.
The preferred embodiments of the present invention provide an outboard motor with an oil pump assembly having a sealing arrangement configured to inhibit leakage of oil from the lubrication system and to inhibit invasion of foreign matter, such as water, into the oil pump.
In accordance with one aspect, the present invention comprises an outboard motor with an engine having a substantially vertically-oriented crankshaft, a driveshaft coupled with the crankshaft of the engine so as to rotate therewith, and a lubrication system to supply lubricant to at least one component of the engine. The lubrication system comprises an oil pump assembly having a housing. The housing defines a pump chamber that at least substantially encircles a portion of the crankshaft. A rotor is disposed within the pump chamber and is configured to rotate with the crankshaft. A first seal member is disposed above the chamber and is configured to sealingly engage the crankshaft. A second seal member is disposed below the chamber and is configured to sealingly engage the crankshaft. A third seal member is disposed below the second seal member and is configured to sealingly engage the driveshaft.
In accordance with another aspect of the present invention, a marine drive comprises an internal combustion engine adapted to drive a propulsion device through a rotating shaft. A lubrication system of the drive comprises an oil pump assembly. The pump assembly comprises a housing configured to circumferentially surround the shaft. The housing also defines a pump chamber. A rotor is arranged within the pump chamber and is configured to rotate with the shaft. A seal arrangement comprises a lower seal member disposed below the pump chamber. The lower seal member includes a seal lip adapted to slidably engage the shaft. The seal lip extends toward the shaft in a downwardly-inclined direction.
In accordance with a further aspect, the present invention provides a marine drive comprising an internal combustion engine and a lubrication system. The engine is configured to drive a propulsion device and includes a rotating vertical shaft. The lubrication system comprises an oil pump assembly configured to be driven by the vertical shaft. The oil pump assembly comprises a housing defining a pump chamber through which the shaft extends. An upper seal member is positioned above the pump chamber and is configured to sealingly engage the shaft. A lower seal member is positioned below the pump chamber and is configured to sealingly engage the shaft. The upper seal member is configured so that oil will leak upwardly past the seal when oil pressure in the chamber exceeds a first threshold value. The lower seal member is configured so that oil will leak downwardly past the seal when oil pressure in the chamber exceeds a second threshold value, and the first threshold value is less than the second threshold value.
In accordance with a still further aspect, an outboard motor comprises a drive unit and a mounting mechanism for mounting the drive unit onto a watercraft. The mounting mechanism comprises at least one dampener adapted to dampen vibrations from the drive unit. The drive unit comprises a reciprocating internal combustion engine configured to drive a shaft as a result of reciprocal movement of at least one component of the engine. The engine comprises a lubrication system for delivering lubricant to at least one component of the engine. The lubrication system includes a lubricant pump positioned vertically higher than the dampener and coupled with the shaft so that the shaft extends through a housing of the lubricant pump. The housing defines a pump chamber therewithin and comprises a first seal member disposed below the pump chamber, a second seal member below the first seal member, and a third seal member below the second seal member. Each of the seal members is disposed circumferentially around the shaft. The first and second seal members are configured to inhibit lubricant from flowing down the shaft past the seal members. The third seal member is configured to inhibit fluids from flowing up the shaft past the third seal member toward the chamber.
In accordance with a yet further aspect, an outboard motor comprises a drive unit and a mounting mechanism for mounting the drive unit onto a watercraft. The mounting mechanism comprises at least one dampener adapted to dampen vibrations from the drive unit. The drive unit comprises a reciprocating internal combustion engine configured to drive a shaft assembly as a result of reciprocal movement of at least one component of the engine. The engine comprises a lubrication system for delivering lubricant to at least one component of the engine. The lubrication system includes a lubricant pump positioned vertically higher than the dampener and coupled with the shaft assembly so that at least a portion of the shaft assembly extends through a housing of the lubricant pump. The housing defines a pump chamber therewithin and comprising a first seal member disposed below the pump chamber, a second seal member below the first seal member, and a third seal member below the second seal member. Each of the seal members is disposed circumferentially around a portion of the shaft assembly. The first and second seal members are configured to inhibit lubricant from flowing down the shaft assembly past the seal members. The third seal member is configured to inhibit fluids from flowing up the shaft assembly past the third seal member and toward the chamber.